三维凸包模板_Hdu 4273 Rescue

使用汝佳的模板: 简单,但是有的题目过不了

acm.hdu.edu.cn/showproblem.php?pid=4273

#include <cstdio>
#include <ctime>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <string>
#include <set>
#include <stack>
#include <map>
#include <cmath>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bitset>
#include <fstream>
using namespace std;


//LOOP
#define FF(i, a, b) for(int i = (a); i < (b); ++i)
#define FE(i, a, b) for(int i = (a); i <= (b); ++i)
#define FED(i, b, a) for(int i = (b); i>= (a); --i)
#define REP(i, N) for(int i = 0; i < (N); ++i)
#define CLR(A,value) memset(A,value,sizeof(A))
#define FC(it, c) for(__typeof((c).begin()) it = (c).begin(); it != (c).end(); it++)


//OTHER
#define SZ(V) (int)V.size()
#define PB push_back
#define MP make_pair
#define all(x) (x).begin(),(x).end()


//INPUT
#define RI(n) scanf("%d", &n)
#define RII(n, m) scanf("%d%d", &n, &m)
#define RIII(n, m, k) scanf("%d%d%d", &n, &m, &k)
#define RIV(n, m, k, p) scanf("%d%d%d%d", &n, &m, &k, &p)
#define RV(n, m, k, p, q) scanf("%d%d%d%d%d", &n, &m, &k, &p, &q)
#define RS(s) scanf("%s", s)


//OUTPUT
#define WI(n) printf("%d\n", n)
#define WS(n) printf("%s\n", n)


//debug
//#define online_judge
#ifndef online_judge
#define debugt(a) cout << (#a) << "=" << a << " ";
#define debugI(a) debugt(a) cout << endl
#define debugII(a, b) debugt(a) debugt(b) cout << endl
#define debugIII(a, b, c) debugt(a) debugt(b) debugt(c) cout << endl
#define debugIV(a, b, c, d) debugt(a) debugt(b) debugt(c) debugt(d) cout << endl
#else
#define debugI(v)
#define debugII(a, b)
#define debugIII(a, b, c)
#define debugIV(a, b, c, d)
#endif

typedef long long LL;
typedef unsigned long long ULL;
typedef vector <int> VI;
const int INF = 0x3f3f3f3f;
const double eps = 1e-10;
const int MOD = 100000007;
const int MAXN = 400;
const double PI = acos(-1.0);

inline int dcmp(double x)
{
    if(fabs(x) < eps) return 0;
    else return x < 0 ? -1 : 1;
}

struct Point
{
    double x, y, z;
    Point(double x=0, double y=0, double z=0):x(x),y(y),z(z) { }
    inline void read() { scanf("%lf%lf%lf", &x, &y, &z); }
};

typedef Point Vector;

inline Vector operator + (Vector A, Vector B)
{
    return Vector(A.x+B.x, A.y+B.y, A.z+B.z);
}
inline Vector operator - (Point A, Point B)
{
    return Vector(A.x-B.x, A.y-B.y, A.z-B.z);
}
inline Vector operator * (Vector A, double p)
{
    return Vector(A.x*p, A.y*p, A.z*p);
}
inline Vector operator / (Vector A, double p)
{
    return Vector(A.x/p, A.y/p, A.z/p);
}

bool operator == (const Point& a, const Point& b)
{
    return dcmp(a.x-b.x) == 0 && dcmp(a.y-b.y) == 0 && dcmp(a.z-b.z) == 0;
}

inline double Dot(Vector A, Vector B)
{
    return A.x*B.x + A.y*B.y + A.z*B.z;
}
inline double Length(Vector A)
{
    return sqrt(Dot(A, A));
}
inline double Angle(Vector A, Vector B)
{
    return acos(Dot(A, B) / Length(A) / Length(B));
}
inline Vector Cross(Vector A, Vector B)
{
    return Vector(A.y*B.z - A.z*B.y, A.z*B.x - A.x*B.z, A.x*B.y - A.y*B.x);
}
inline double Area2(Point A, Point B, Point C)
{
    return Length(Cross(B-A, C-A));
}
inline double Volume6(Point A, Point B, Point C, Point D)
{
    return Dot(D-A, Cross(B-A, C-A));
}
inline Point Centroid(Point A, Point B, Point C, Point D)
{
    return (A + B + C + D)/4.0;
}

inline double rand01()
{
    return rand() / (double)RAND_MAX;
}
inline double randeps()
{
    return (rand01() - 0.5) * eps;
}

inline Point add_noise(Point p)
{
    return Point(p.x + randeps(), p.y + randeps(), p.z + randeps());
}

struct Face
{
    int v[3];
    Face(int a, int b, int c)
    {
        v[0] = a;
        v[1] = b;
        v[2] = c;
    }
    inline Vector Normal(const vector<Point>& P) const
    {
        return Cross(P[v[1]]-P[v[0]], P[v[2]]-P[v[0]]);
    }
    // f是否能看见P[i]
    inline int CanSee(const vector<Point>& P, int i) const
    {
        return Dot(P[i]-P[v[0]], Normal(P)) > 0;
    }
};

// 增量法求三维凸包
// 注意：没有考虑各种特殊情况（如四点共面）。实践中，请在调用前对输入点进行微小扰动
vector<Face> CH3D(const vector<Point>& P)
{
    int n = P.size();
    vector<vector<int> > vis(n);
    for(int i = 0; i < n; i++) vis[i].resize(n);

    vector<Face> cur;
    cur.push_back(Face(0, 1, 2)); // 由于已经进行扰动，前三个点不共线
    cur.push_back(Face(2, 1, 0));
    for(int i = 3; i < n; i++)
    {
        vector<Face> next;
        // 计算每条边的“左面”的可见性
        for(int j = 0; j < (int)cur.size(); j++)
        {
            Face& f = cur[j];
            int res = f.CanSee(P, i);
            if(!res) next.push_back(f);
            for(int k = 0; k < 3; k++) vis[f.v[k]][f.v[(k+1)%3]] = res;
        }
        for(int j = 0; j < (int)cur.size(); j++)
            for(int k = 0; k < 3; k++)
            {
                int a = cur[j].v[k], b = cur[j].v[(k+1)%3];
                if(vis[a][b] != vis[b][a] && vis[a][b]) // (a,b)是分界线，左边对P[i]可见
                    next.push_back(Face(a, b, i));
            }
        cur = next;
    }
    return cur;
}

struct ConvexPolyhedron
{
    int n;
    vector<Point> P, P2;
    vector<Face> faces;

    bool read()
    {
        if(scanf("%d", &n) != 1) return false;
        P.resize(n);
        P2.resize(n);
        for(int i = 0; i < n; i++)
        {
            P[i].read();
            P2[i] = add_noise(P[i]);
        }
        faces = CH3D(P2);
        return true;
    }

    Point centroid()
    {
        Point C = P[0];
        double totv = 0;
        Point tot(0,0,0);
        for(int i = 0; i < (int)faces.size(); i++)
        {
            Point p1 = P[faces[i].v[0]], p2 = P[faces[i].v[1]], p3 = P[faces[i].v[2]];
            double v = -Volume6(p1, p2, p3, C);
            totv += v;
            tot = tot + Centroid(p1, p2, p3, C)*v;
        }
        return tot / totv;
    }

    double mindist(Point C)
    {
        double ans = 1e30;
        for(int i = 0; i < (int)faces.size(); i++)
        {
            Point p1 = P[faces[i].v[0]], p2 = P[faces[i].v[1]], p3 = P[faces[i].v[2]];
            ans = min(ans, fabs(-Volume6(p1, p2, p3, C) / Area2(p1, p2, p3)));
        }
        return ans;
    }
} P1;

int main()
{
    ConvexPolyhedron P1, P2;
    while(P1.read())
    {
        Point C1 = P1.centroid();
        double d1 = P1.mindist(C1);
        printf("%.3lf\n", d1);
    }
    return 0;
}